WHAT IS MICROWAVE ABLATION?
A PATIENT INTRODUCTION

Microwave ablation — often shortened to MWA — is a way of destroying small tumours using heat. A thin antenna is placed directly into the tumour through the skin, and electromagnetic microwave energy is delivered through the antenna to heat the surrounding tissue to temperatures that kill cancer cells. No large incisions are needed; the procedure is image-guided and typically performed under sedation.

“A microwave oven heats food. The same physics — at carefully controlled power, duration, and antenna design — can destroy small tumours from inside the body.”

• How It Destroys Cancer Cells

  Microwave energy causes water molecules inside cells to vibrate rapidly, generating intense heat. Within minutes, temperatures around the antenna reach 100–150°C, killing cells through coagulative necrosis — essentially cooking the tumour tissue in place. The body then gradually clears the dead tissue over weeks.

• What Equipment Is Used

  A microwave generator connected to a thin antenna (typically 14–17 gauge — a little thicker than a standard IV needle). Image guidance comes from CT scanner, ultrasound, or occasionally MRI. The antenna is connected to a cooling system to keep the shaft cool while the tip delivers high temperatures at the tumour.

MWA is most useful for small tumours in solid organs where minimally invasive treatment makes sense — either because surgery is not the right option, or because ablation offers comparable outcomes with less recovery time.

• Hepatocellular Carcinoma (Liver Cancer)

  The best-established MWA indication. For small HCC tumours (typically <3 cm, sometimes up to 5 cm) in patients with cirrhosis, MWA offers outcomes comparable to surgical resection with substantially less morbidity. Often used in patients whose liver function would not tolerate surgical resection.

• Colorectal Liver Metastases

  For patients with limited liver metastases from colorectal cancer (typically <5 lesions, each <3 cm) who are not surgical candidates or who have already had liver surgery, MWA can provide local control. Often combined with systemic chemotherapy as part of a multi-modal plan.

• Stage I Non-Small-Cell Lung Cancer

  For patients with early-stage lung cancer who are not surgical candidates due to lung function or comorbidities, MWA offers a curative-intent option. Outcomes are studied alongside stereotactic body radiation therapy (SBRT) as alternatives to surgery.

• Pulmonary Metastases (Lung Mets from Other Cancers)

  For oligometastatic disease in the lung — from colorectal, renal, sarcoma, or other primary cancers — MWA offers local control of individual lesions. Often used when patients have a limited number of lung metastases and need to preserve lung function.

• Kidney, Adrenal, and Other Indications

  Small renal cell carcinomas (especially in patients who cannot have surgery), selected adrenal masses, benign musculoskeletal lesions like osteoid osteoma, and palliative bone metastases also use MWA. Indications continue to expand as evidence accumulates.

A typical MWA procedure from pre-procedure preparation through recovery and discharge.

1. 1

   Step 1: Pre-Procedure Preparation

   Pre-procedure consultation includes review of recent imaging, blood tests (coagulation, kidney function), discussion of fasting requirements (typically 6 hours before), and informed consent. Patients on blood thinners receive instructions about pausing medications.

2. 2

   Step 2: Arrival and Sedation

   On the day of the procedure, IV access is established and conscious sedation (or general anaesthesia for some patients) is given. Patient is positioned for optimal access to the tumour — typically lying on the back or side depending on location.

3. 3

   Step 3: Imaging Guidance and Antenna Placement

   CT scanner or ultrasound is used to precisely locate the tumour. Local anaesthetic is injected at the entry point. The MWA antenna is advanced through the skin and into the tumour under continuous image guidance.

4. 4

   Step 4: Ablation Energy Delivery

   Microwave energy is delivered through the antenna for 5–10 minutes per ablation. Larger tumours may require multiple antenna positions or multiple antennae simultaneously. Real-time imaging monitors the ablation zone forming around the antenna tip.

5. 5

   Step 5: Confirmation and Antenna Removal

   Post-ablation imaging confirms complete tumour coverage with an adequate margin (typically 5–10 mm beyond visible tumour edge). The antenna is withdrawn with brief tract ablation to prevent bleeding and tumour seeding.

6. 6

   Step 6: Recovery and Discharge

   Recovery in observation area for 2–4 hours. Most patients are discharged the same day or after one overnight stay. Minor discomfort and low-grade fever for 24–48 hours (post-ablation syndrome) are common and self-limited.

Both treatments aim for tumour cure, but they suit different patients.

A balanced look at what MWA does well and where it falls short — useful for patients considering ablation as an alternative to surgery, radiation, or other treatments.

• Procedural Efficiency

  A typical single-tumour MWA procedure takes 30–60 minutes from start of imaging to antenna removal. Compared to RFA, MWA is faster and produces larger, more uniform ablation zones in less time. This efficiency translates to shorter sedation and quicker recovery.

• Less Affected by Heat-Sink Effect

  Tumours near large blood vessels are difficult to ablate with RFA because flowing blood carries heat away (heat-sink effect), leaving incomplete ablation. MWA generates heat faster and at higher temperatures, overcoming much of the heat-sink limitation — making it preferred for tumours adjacent to major vessels.

• Limited to Smaller Tumours

  MWA is most effective for tumours <3 cm; effectiveness declines as tumour size increases. For tumours >5 cm, surgical resection or trans-arterial therapies often provide better outcomes. Multiple-antenna techniques can extend the size range but with increasing complexity.

• Location-Dependent Risk

  Tumours close to bowel, gallbladder, major bile ducts, or other heat-sensitive structures carry higher risk of collateral damage. Lung tumours close to the chest wall or major airways require careful technique. Some locations make ablation inadvisable.

Explore the full microwave ablation knowledge base.

Frequently Asked Questions

Common questions patients ask about microwave ablation.